Hydrogen generation systems and methods utilizing sodium silicide and sodium silica gel materials

ABSTRACT

Systems, devices, and methods combine thermally stable reactant materials and aqueous solutions to generate hydrogen and a non-toxic liquid by-product. The reactant materials can sodium silicide or sodium silica gel. The hydrogen generation devices are used in fuels cells and other industrial applications. One system combines cooling, pumping, water storage, and other devices to sense and control reactions between reactant materials and aqueous solutions to generate hydrogen. Springs and other pressurization mechanisms pressurize and deliver an aqueous solution to the reaction. A check valve and other pressure regulation mechanisms regulate the pressure of the aqueous solution delivered to the reactant fuel material in the reactor based upon characteristics of the pressurization mechanisms and can regulate the pressure of the delivered aqueous solution as a steady decay associated with the pressurization force. The pressure regulation mechanism can also prevent hydrogen gas from deflecting the pressure regulation mechanism.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Divisional application of U.S. patent applicationSer. No. 13/761,452, filed Feb. 7, 2013, which claims benefit ofpriority of U.S. Provisional Patent Application Ser. No. 61/164,888filed on Mar. 30, 2009, U.S. Provisional Patent Application Ser. No.61/185,579 filed on Jun. 6, 2009, and U.S. patent application Ser. No.12/750,527 filed on Mar. 30, 2010, and U.S. Provisional PatentApplication Ser. No. 61/595,841 filed on Feb. 7, 2012, the entiredisclosures of which are incorporated herein by reference. Thisapplication is a continuation-in-part of U.S. patent application Ser.No. 12/750,527 filed on Mar. 30, 2010.

FEDERALLY-SPONSORED RESEARCH AND DEVELOPMENT

This invention was made with government support under contract numberDEFG36-08G088108 awarded by the U.S. Department of Energy. The U.S.Government has certain rights in this invention.

TECHNOLOGICAL FIELD

This technology generally relates to systems and methods of generatinghydrogen using a reactant fuel material and an aqueous solution, andmore particularly, to systems and methods for generating hydrogen usingsodium silicide, sodium silica gel, or multi-component mixtures whenreacted with water, water solutions, heat, or pH change.

BACKGROUND

Fuel cells are electrochemical energy conversion devices that convert anexternal source fuel into electrical current. Many common fuel cells usehydrogen as the fuel and oxygen (typically from air) as an oxidant. Theby-product for such a fuel cell is water, making the fuel cell a verylow environmental impact device for generating power.

Fuel cells compete with numerous other technologies for producing power,such as the gasoline turbine, the internal combustion engine, and thebattery. A fuel cell provides a direct current (DC) voltage that can beused for numerous applications including: stationary power generation,lighting, back-up power, consumer electronics, personal mobilitydevices, such as electric bicycles, as well as landscaping equipment,and others. There are a wide variety of fuel cells available, each usinga different chemistry to generate power. Fuel cells are usuallyclassified according to their operating temperature and the type ofelectrolyte system that they utilize. One common fuel cell is thepolymer exchange membrane fuel cell (PEMFC), which uses hydrogen as thefuel with oxygen (usually air) as its oxidant. It has a high powerdensity and a low operating temperature of usually below 80° C. Thesefuel cells are reliable with modest packaging and system implementationrequirements.

The challenge of hydrogen storage and generation has limited thewide-scale adoption of PEM fuel cells. Although molecular hydrogen has avery high energy density on a mass basis, as a gas at ambient conditionsit has very low energy density by volume. The techniques employed toprovide hydrogen to portable applications are widespread, including highpressure and cryogenics, but they have most often focused on chemicalcompounds that reliably release hydrogen gas on-demand. There arepresently three broadly accepted mechanisms used to store hydrogen inmaterials: absorption, adsorption, and chemical reaction.

In absorptive hydrogen storage for fueling a fuel cell, hydrogen gas isabsorbed directly at high pressure into the bulk of a specificcrystalline material, such as a metal hydride. Most often, metalhydrides, like MgH2, NaAlH4, and LaNi5H6, are used to store the hydrogengas reversibly. However, metal hydride systems suffer from poor specificenergy (i.e., a low hydrogen storage to metal hydride mass ratio) andpoor input/output flow characteristics. The hydrogen flowcharacteristics are driven by the endothermic properties of metalhydrides (the internal temperature drops when removing hydrogen andrises when recharging with hydrogen). Because of these properties, metalhydrides tend to be heavy and require complicated systems to rapidlycharge and/or discharge them. For example, see U.S. Pat. No. 7,271,567for a system designed to store and then controllably release pressurizedhydrogen gas from a cartridge containing a metal hydride or some otherhydrogen-based chemical fuel. This system also monitors the level ofremaining hydrogen capable of being delivered to the fuel cell bymeasuring the temperature and/or the pressure of the metal hydride fuelitself and/or by measuring the current output of the fuel cell toestimate the amount of hydrogen consumed.

In adsorption hydrogen storage for fueling a fuel cell, molecularhydrogen is associated with the chemical fuel by either physisorption orchemisorption. Chemical hydrides, like lithium hydride (LiH), lithiumaluminum hydride (LiAlH4), lithium borohydride (LiBH4), sodium hydride(NaH), sodium borohydride (NaBH4), and the like, are used to storehydrogen gas non-reversibly. Chemical hydrides produce large amounts ofhydrogen gas upon its reaction with water as shown below:NaBH4+2 Hz0−7NaBOz+4 HzTo reliably control the reaction of chemical hydrides with water torelease hydrogen gas from a fuel storage device, a catalyst must beemployed along with tight control of the water's pH. Also, the chemicalhydride is often embodied in a slurry of inert stabilizing liquid toprotect the hydride from early release of its hydrogen gas. The chemicalhydride systems shown in U.S. Pat. Nos. 7,648,786; 7,393,369; 7,083,657;7,052,671; 6,939,529; 6,746,496; and 6,821,499, exploit at least one,but often a plurality, of the characteristics mentioned above.

In chemical reaction methods for producing hydrogen for a fuel cell,often hydrogen storage and hydrogen release are catalyzed by a modestchange in temperature or pressure of the chemical fuel. One example ofthis chemical system, which is catalyzed by temperature, is hydrogengeneration from ammonia-borane by the following reaction:NH₃BH₃→NH₂BH₂+H₂→NHBH+H₂The first reaction releases 6.1 wt. % hydrogen and occurs atapproximately 120° C., while the second reaction releases another 6.5wt. % hydrogen and occurs at approximately 160° C. These chemicalreaction methods do not use water as an initiator to produce hydrogengas, do not require a tight control of the system pH, and often do notrequire a separate catalyst material. However, these chemical reactionmethods are plagued with system control issues often due to the commonoccurrence of thermal runaway. See, for example, U.S. Pat. No.7,682,411, for a system designed to thermally initialize hydrogengeneration from ammonia-borane and to protect from thermal runaway. See,for example, U.S. Pat. Nos. 7,316,788 and 7,578,992, for chemicalreaction methods that employ a catalyst and a solvent to change thethermal hydrogen release conditions.

In view of the above, there is a need for an improved hydrogengeneration system and method that overcomes many, or all, of the aboveproblems or disadvantages in the prior art.

SUMMARY

The hydrogen generation system described below accomplishes asubstantially complete reaction of reactant fuel material, such as astabilized alkali metal material, including sodium silicide and/orsodium-silica gel, which do not contain any stored hydrogen gas ormolecular hydrogen atoms. Additional reactants can include chemicalhydrides, such as sodium borohydride (NaBH4), and/or ammonia borane, andthe like. Also, the system reaction employing these reactants does notrequire an additional catalyst chamber, and is easily start-stopcontrolled by the simple addition of an appropriate aqueous medium tosatisfy the hydrogen demand of a fuel cell or hydrogen-drawing system.In addition, the examples below meet all of the above requirements whileminimizing overall system volume and weight.

One example in the present disclosure is a reactor including a reactantfuel material, which generates hydrogen when the reactant fuel materialis exposed to an aqueous solution. The reactor may be a standalonehydrogen generation component which can contain the aqueous solution andits control system. Similarly, another example can include a reactor towhich an aqueous solution is introduced by an external supply. Thehydrogen generation may also be controlled, monitored, or processed byan external control system. The control system and reactor can operateas a standalone hydrogen generation system used to provide hydrogen tohydrogen fuel cells or for any general, laboratory, industrial, orconsumer use. Likewise, the control system and reactor can beimplemented in whole or in part within a complete fuel cell systemsupplying an end product such as a laptop computer, personal orcommercial electronics products, and other devices and equipment thatrequire a power source.

One method of generating hydrogen gas includes inserting a reactant fuelmaterial into a reactor and combining an aqueous solution with thereactant fuel material in the reactor to generate hydrogen gas.

The reactant fuel material can include stabilized alkali metal materialssuch as silicides, including sodium silicide powder (NaSi), andsodium-silica gel (Na—SG). The stabilized alkali metal materials canalso be combined with other reactive materials, including, but notlimited to, ammonia-borane with, or without, catalysts, sodiumborohydride mixed with, or without, catalysts, and an array of materialsand material mixtures that produce hydrogen when exposed to heat, pH, oraqueous solutions. The mixture of materials and the aqueous solutionscan also include additives to control the pH of the waste products, tochange the solubility of the waste products, to increase the amount ofhydrogen production, to increase the rate of hydrogen production, and tocontrol the temperature of the reaction. The aqueous solution caninclude water, acids, bases, alcohols, salts, oils, and mixtures ofthese solutions. Examples of the aqueous solutions can include methanol,ethanol, hydrochloric acid, acetic acid, sodium hydroxide, and the like.The aqueous solutions can also include additives, such as a coreactantthat increases the amount of H2 produced, a flocculant, a corrosioninhibitor, or a thermophysical additive that changes thermophysicalproperties of the aqueous solution. Example flocculants include calciumhydroxide, sodium silicate, and others, while corrosion inhibitors caninclude phosphates, borates, and others. Further, the thermophysicaladditive can change the temperature range of the reaction, the pressurerange of the reaction, and the like. Further, the additive to theaqueous solution can include mixtures of a variety of differentadditives.

The reactor can be a standalone, replaceable component, which enables acontrol system or a fuel cell system to utilize multiple reactors. Thereactor may also be termed a cartridge, cylinder, can, vessel, pressurevessel, module, and/or enclosure. The reactor includes the reactant fuelmaterial and either the aqueous solution inside the reactor or an inletport, or a plurality of inlet ports, from which the aqueous solution isintroduced into the reactor. The reactor can also have an output portfor hydrogen gas, which may undergo additional processing (e.g., vaporcondensation, purification, regulation, and the like) once it leaves thereactor and prior to being supplied to an external system, like a fuelcell.

The aqueous solution may be initially stored or added by the userexternally or returned from a fuel cell system into the aqueous solutioninput port on the reactor. The aqueous solution can be added to thereactant fuel material, including stabilized alkali metals, in thereactor via the inlet port(s) using a pump, such as a manual pump, abattery powered pump, an externally powered pump, a spring controlledpump, and the like, or another aqueous delivery mechanism, such aspressure differential and diffusion. The aqueous solution can be storedwithin the reactor and separated from the reactant fuel material by apiston, bag, membrane, or other separation device.

The reactor may have the hydrogen output and the aqueous solution inputas part of one connection to one device or control system. The reactormay have the hydrogen output connected to one device or control systemand the water input connected to a different device or 6 control system.The reactor may have only a hydrogen output with internal controlscombining the reactant fuel material with the aqueous solution.

The method of generating hydrogen gas can also include filtering thegenerated hydrogen gas, absorbing by-products in the hydrogen gas,and/or condensing water from the generated hydrogen gas. This filtrationcan occur inside or outside the reactor, inside the control system, orin both. For example, a hydrogen separation membrane can be used ineither the reactor or in the control system (or in both) to filter thehydrogen, while a condenser unit can be used to condense the water fromthe generated hydrogen gas. Filters and condensers can act upon thegenerated hydrogen gas as it exits the hydrogen outlet port of thereactor. The filtered hydrogen gas and/or the condensed water can berecycled back to the reactor or to a water storage container. Ingenerating hydrogen gas, a waste product can be created, such as sodiumsilicate or other reaction waste products.

In one example, a control system can include a monitoring device tomonitor parameters of the reaction of the reactant fuel material and theaqueous solution in the reactor. The monitoring device can monitor oneor multiple parameters in or on the reactor or in an external controlsystem. These parameters can include, but are not limited to,temperature, electrical conductivity of the reactor contents, pressurein the reactor, weight of reaction, amount of un-reacted reactant fuelmaterial, elapsed time of reaction, amount of aqueous solution in thereactor, and a maximum amount of aqueous solution to be added to thereactor. The monitored system characteristic can then be displayed, orused in a calculation to modify the control strategy, communicate thereactor status or system status with other devices, or communicate thecharacteristic or a derivative characteristic to a user. An example of auser communication device is a visual display device, such as an LCDdisplay, or a viewport to see the remaining level of water, for example.

The reaction can be controlled in association with the monitoring deviceusing a reaction control device. Examples of reaction control devicesinclude, but are not limited to, devices to alter temperature,electrical conductivity range, pressure, weight of reaction, as well asother environmental measures within which the combination of thereactant fuel material and the aqueous solution in the reactor proceed.For example, reaction control devices can be used to add additionalreactant fuel materials to the reactor, add additional aqueous solutionto the reactor, remove a waste product from the reactor, cool thereactor, heat the reactor, mix a combination of the reactant fuelmaterials and the aqueous solution, bleed the reactor to decrease thepressure, and to perform other control measures.

Measuring reaction parameters and using reaction control devices allowsthe method of generating hydrogen gas to be controlled in the reactorwhen any of the environmental measures within the reactor is outside arespective range or by a control strategy that monitors and processesthe rate of change of any of the parameters.

The reactor can include a number of different filters to separate thereactants and its reaction by-products from the hydrogen gas. Forexample, the methods of generating clean hydrogen gas can include bothseparating and filtering steps. In one example, at least one of thereactant fuel materials, the aqueous solution, the hydrogen gas, and/orthe reaction waste products are separated from the others. Also, thehydrogen gas can be purified using a hydrogen separation membrane, achemical filter, a desiccant filter, a coarse media filter, a dryerfilter, and/or a secondary reactor chamber. As they are used, thefilters can be cleaned with a portion of the aqueous solution as theaqueous solution is inputted into the reactor.

The reactor can also include structures and devices for aqueous solutiondistribution such as a plumbing network, nozzle arrays, flow limiters,and water distribution media such as diffusers, misters, and the like.The aqueous solution can be distributed through multiple points in thereactor in parallel, in series, or in a combination thereof. The aqueoussolution distribution system can be used in whole, or in part, to reactwith the reactant fuel material to produce hydrogen, to purify thehydrogen stream, to clean filter media, and/or to control the wasteproduct parameters.

The reactor can include hydrogen handling components such as a safetyrelief mechanism such as a relief valve, burst disc, or a controlledreactor burst point. The reactor may also include an exit flow limiterto minimize, or control, the hydrogen output rate in order to supply arequired fuel cell characteristic or to match the transient flow ratelimitations of the filtration components.

The system of generating hydrogen gas can also include a pressuretransducer, a relief valve, a hydrogen-sealing check valve, a fan, aheat exchanger, and a reactor cooling source. Likewise, the system caninclude a recapture container for recycling fuel cell reaction wastesolution and returning the recycled fuel cell reaction waste solution tothe reactor.

The methods of generating hydrogen can also include directing a portionof the aqueous solution to areas of the reactor to recapture the wasteproduct resulting from the combination of the reactant fuel material andthe aqueous solution. For example, a portion of the aqueous solution canbe added to a secondary reactor chamber, and the generated hydrogen gascan be passed through this portioned aqueous solution. Filtering canalso be performed using a liquid permeable screen to separate a wasteproduct from un-reacted reactant fuel material and aqueous solution.

These and other advantages, aspects, and features will become moreapparent from the following detailed description when viewed inconjunction with the accompanying drawings. Non-limiting andnon-exhaustive embodiments are described with reference to the followingdrawings. Accordingly, the drawings and descriptions below are to beregarded as illustrative in nature, and not as restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an example of a hydrogen generation system using astabilized alkali metal material and an aqueous solution to providehydrogen to a hydrogen fuel cell or a general laboratory, industrial, orconsumer use.

FIG. 2 illustrates an example of a hydrogen generation system with tworeactors and a carry-handle accessory.

FIG. 3 shows an example hydrogen gas generation system that includes areactor, a water container, and a number of additional components.

FIGS. 4A-4D illustrate reactors employing multiple water dispensingnozzles at select locations.

FIG. 5 schematically illustrates an example hydrogen generation systemwith a heat removal structure.

FIG. 6 shows an example hydrogen generation system with a hydrogenoutlet and water inlet at one end of the reactor in a downwardorientation to mix the reaction components.

FIG. 7 shows an exploded view of a hydrogen generation system with theheat removal structure shown in FIGS. 5 and 6.

FIG. 8 shows a hydrogen generation system configuration with a coarsemedia filter and a hydrogen filtration membrane.

FIGS. 9A-9C illustrate a water feed network and a comparison of filterareas without a water feed network and those utilizing the water feednetwork.

FIGS. 10A-10B illustrate alternative filter designs to a membrane/coarsefilter system.

FIGS. 11A-11B illustrate systems and techniques of waste capture andcirculation.

FIG. 12A illustrates an example of a reactor with multiple reactioncompartments.

FIG. 12B illustrates an example reactor with multiple protectiveinsulation devices.

FIG. 13 illustrates an example reactor with electrical contacts tomeasure changes in conductivity.

FIG. 14 illustrates an example reactor with electrical contactsconnected to a pressure vessel cap of the reactor.

FIGS. 15A-15C shows an example lightweight, low-cost, reusable reactorin accordance with the claimed invention.

FIG. 16 shows an example architecture of a low output reactor system inaccordance with the claimed invention.

FIG. 17 shows a detailed example of a low output reactor system inaccordance with the claimed invention.

FIG. 18 shows a reactor with solid reactant fuel material connected by avalve to a spring-based liquid pump system.

FIG. 19 shows a graphical depiction of oscillatory hydrogen generationover time in a spring-based liquid pump system without a coupling valve.

FIG. 20 shows a graphical depiction of hydrogen generation pressure overtime in a spring-based liquid pump system with a coupling valve.

FIG. 21 shows a reactor with reactant fuel material and a spring basedliquid pump system integrated within a single cartridge.

FIG. 22A shows a reactor with reactant fuel material and an integratedspring based liquid pump system.

FIG. 22B shows three primary sub-assemblies of an integrated cartridgewith a reactor and spring based liquid pump system.

FIG. 23 shows a perspective view and cross-section of an integratedcartridge with a reactor and spring based liquid pump system.

FIG. 24 shows an assembly view of an integrated cartridge.

FIG. 25 illustrates water feed distribution mechanisms.

FIG. 26 shows a threaded locking mechanism to couple a separable liquidfeed/reactor hydrogen generation device.

FIG. 27 shows a schematic representation of a separable liquidfeed/reactor hydrogen generation device.

FIG. 28 shows a schematic representation of a separable liquidfeed/reactor hydrogen generation device with a conical/collapsingspring.

FIGS. 29A-29B depict normal and compressed views of a collapsible springto facilitate limited variability in force over travel.

FIG. 30A shows a perspective view of a hydrogen generation cartridgewith a spring based liquid feed and a volume exchanging system.

FIG. 30B shows a schematic representation of a hydrogen generationcartridge with a spring based liquid feed and a volume exchangingsystem.

FIG. 31 shows perspective and cross-sectional views of a hydrogengeneration cartridge with a volume exchanging, spring based liquid feed.

FIG. 32 shows an assembly view and a cross-sectional view of a hydrogengeneration cartridge with volume exchanging, spring based liquid feed.

FIG. 33 shows an assembly view of an integrated cartridge filtrationsystem example.

FIG. 34 shows an assembly view of a normally closed valve to separate areactor and a liquid feed.

FIGS. 35A-B show an assembly view and a perspective view of a matingcomponent to join a reactor and a liquid feed.

DETAILED DESCRIPTION

In the examples below, reference is made to hydrogen fuel cell systems,but it should be understood that the systems and methods discussed canalso be implemented in any hydrogen gas generation application, such aslaboratory applications, commercial or industrial applications, andconsumer applications, for example.

Basic Hydrogen Control System

In one example, sodium silicide and/or sodium silica gel can be combinedwith water to generate hydrogen gas, but the developed technologies canalso use other stabilized alkali metal materials, such as dopedsilicides and silicides that have hydrogen in association, or solidpowders combined with aqueous solutions to produce hydrogen gas.Additionally, many aspects of the developed system technology can alsobe applied to alternative materials used in hydrogen production such asaluminum powder, or any other material, or combination of materials,that generates hydrogen when exposed to aqueous solutions.

The reactant fuel materials can be free-flowing powders or materialsthat can be compressed, molded, cut or formed into rods, cones, spheres,cylinders or other physical geometries. The materials may consist ofvariable powder sizes, geometric variations, material coatings, ormaterial variations to control the reaction rate. One method for coatingwould be to expose the solid sodium silicide structure to humid aircreating a sodium silicate barrier which is dissolvable in water. Othercoating materials can include dissolvable or removable waxes, plastics,gels, salts, or proteins. Of course other forms and geometries for thereactant fuel materials and aqueous solutions may be used with which tocombine the reactant fuel materials and aqueous solutions.

FIG. 1 shows an example of a hydrogen generation system 100 using areactant fuel material and an aqueous solution to generate hydrogen gas.The generated hydrogen gas can be directed to a hydrogen fuel cell or toa general laboratory, industrial, or consumer use. The reactant fuelmaterial 101 can be inserted into a reactor 102. In this disclosure, theterms reactor, cartridge, and pressure vessel are used synonymously toidentify a container or other receptacle in which a reactant fuelmaterial is placed. In the example shown in FIG. 1, a removable reactor102 is attached to a water inlet connection 106 and a hydrogen outletconnection 108. 12. The connections can include, but are not limited to,normally-closed double-shut-off valves and/or normally closed checkvalves. The connections from the reactor 102 to the water inletconnection 106 and hydrogen outlet connection 108 can be flexibleconnections or can be rigid connections, depending upon the particularuse. Water, or another aqueous solution, is added to the reactant fuelmaterial, such as a stabilized alkali metal 101 to generate hydrogen gasand a by-product, such as sodium silicate. The hydrogen gas moves upwardand exits the reactor 102. Although a single reactor 102 is illustratedin FIG. 1, it should be understood that any number of removable or fixedreactors of rigid or flexible construction can be used in the exemplaryhydrogen gas generation systems described. For example, in FIG. 2, tworemovable reactors 202, 204 are shown. Further, the reactors can besecured in place in the system using a locking mechanism, a clip, orother similar securing device.

In the example shown in FIGS. 1 and 2, an aqueous solution, like water,is added to fill ports 110, 210, respectively. In anotherimplementation, a removable water container can be used, such as watercontainer 114, with or without a fill port. In other examples, a reactorcan be pre-filled with reactant fuel material and/or aqueous solution.The aqueous solution can include additives to improve reactionefficiencies, increase hydrogen production, increase the rate ofhydrogen production, reduce contaminant formation, facilitatecontaminant filtration, support final hydrolysis, reduce corrosion,control the pH of the reaction or waste products, change the solubilityof the waste products, and extend temperature range operation, as wellas affect other reaction parameters such as the thermophysicalproperties of the reactants. For example, the additives can includeacids, bases, salts, alcohols, other additives, and mixtures of theseadditives. Examples of the additives can include methanol, ethanol,hydrochloric acid, acetic acid, sodium hydroxide, calcium hydroxide,sodium silicate, phosphates, borates, and others. Other additives can becombined with the reactant fuel material, including boron, carbon, andnitrogen to improve the hydrogen capacity, kinetics and/or to reducereaction enthalpy. With regard to temperature range operation, saltand/or other additives can be included in the aqueous solution to reducethe freezing point of the solution.

The amount of aqueous solution stored in its container can varydepending on system implementation specifics. For example, in FIG. 2,the container can store more than a sufficient volume of aqueoussolution to react multiple cartridges 202, 204. The system can include acondenser (not shown) to condense water from the hydrogen output streamand either return it directly to the reactor, or direct it to the watercontainer 114. The system can include a water inlet connection 106 foran external water source (not shown) to supply additional water to thewater container 114, or in a separate implementation directly to thereactor. In one implementation, fuel cell reaction waste water can becaptured in full or in part and also contribute to the water supply toreduce the net total water requirements.

For example, the sodium silicate waste product readily absorbs water,and its viscosity changes accordingly. By separating the waste productfrom the un-reacted reactant fuel material, the reaction can becontrolled. For example, one end of the reactor can be heated orinsulated to create a solubility condition where excess water exists.This water can then either be pumped back up to the stabilized alkalimetal powder or allowed to react with an amount of sodium silicideconfigured exclusively for water usage maximization. Alternatively, atthe point of reaction, the waste silicate is warm requiring little waterto be in a liquid phase. At the point of reaction, a separation screenis utilized to separate the liquid waste from the unreacted reactantfuel material.

Additional System Components

In addition to the reactor and the aqueous solution sources, thehydrogen gas generation systems can include additional systemcomponents. For example, FIG. 3 shows an example hydrogen gas generationsystem 300 that includes a reactor 302, a water container 314, and anumber of additional components. For example, water source inlet 306allows the filling, or refilling, of water container 314 as needed.Water from water container 314 may be pumped into reactor 302 via watersupply line 390 using a pump 320, such as a peristaltic pump, a manualpump, positive displacement pumps, and other pumps. A pressuretransducer 322 may be placed in line with water supply line 390 and usedto regulate the amount of water pumped into the reactor 302. Forexample, pressure transducer 322 may be used with a pump 320 to deliverpressure calibrated amounts of water to multiple reactors through amultipart valve 324. Pressure transducer 322 may also be used in part toprovide a fail-safe mode to prevent excess water from being pumped intothe reactor 302. In one example, the output voltage of pressuretransducer 322 can be compared to a system voltage parameter using acomparator (not shown). The output of the comparator can be evaluated todetermine if the voltage is in a proper operational range. When thevoltage is in the operational range, additional circuitry implementinginstructions from microcontroller 387 can drive pump 320 to providewater to the reactor 302. When the voltage is outside the operationalrange, the pump 320 is disabled. This circuitry can use a capacitor, orother timing circuits, to create a delay in the reading of the pump toallow an instantaneously high reading during a diaphragm pump action forexample. For hydrogen generation systems with multiple reactors, asupply valve 324 can be used to select which reactor receives water.

The hydrogen gas generation system 300 can include a battery 388 tooperate the pump 320 and/or to otherwise initiate the reaction and tooperate other control electronics (shown collectively as 386). Thehydrogen gas generation system 300 can also receive external power toeither recharge the battery 388 from any external source such as a fuelcell, a wall outlet, or power from any other source. The system 300 mayalso include a small fuel cell system (not shown) to internally operateits internal balance-of-plant components. In one implementation, nobattery is present in isolation, but rather power is obtained from afuel cell or a fuel cell battery hybrid that is either internal to theoverall system 300 or external to the hydrogen generation system 300. Inone implementation, no battery is required if the reactors are given afactory over-pressure of hydrogen, which provides enough hydrogen tostart the system. Furthermore, the hydrogen generation system can bedesigned with a small manually operated pump (such as a syringe or thelike) to start the reaction by a physical user interaction rather thanan electrical start.

Similar to pressure transducer 322, a check valve 326 can be used in thereactor 302, or in the control system, to keep hydrogen pressure inreactor 302 from pushing unallowably high pressures on control systemcomponents such as valves 324 I 361, transducer 322, and/or pumps 320.For example, as the initial water enters the reactor 302 and reacts withreactant fuel material 301 in the reactor 302, hydrogen is generated,and the hydrogen pressure in the reactor 302 builds until the hydrogenreaches a system pressure parameter value upon which the hydrogen gas isrouted out of the reactor 302 and is used elsewhere. In some situations,the pressure in the reactor 302 can exceed that of the capabilities ofthe pump 320 and other system components. Check valve 326 can be used toprevent the pump 320, water container 314, and water line 390 frombecoming excessively pressurized and to prevent damage to the system.Check valve 326 can be used to determine the pressure in the reactor 302and to isolate the amount of pressure to the control system from thereactor 302.

Similarly, hydrogen output check valves 336, 337 manage backflow in thereactor 302. Backflow may occur when the system is used at highaltitudes or when the hydrogen outputs of multiple canisters are tied toeach other. Check valves and transducers in each reactor, and throughoutthe control system, allow for independent pressure readings of eachreactor for systems that use multiple reactors. The hydrogen gas outputlines 391 from each reactor 302 can include a pressure transducer 340,located in the reactor 302 or in the control system 303. In oneimplementation, the check valve 336 only allows hydrogen to flow out ofthe canister as opposed to air entering the canister when beingconnected and disconnected, or in the event that the system isinadvertently connecting high pressure from another source to a reactor.In another implementation, this check valve 336 is not required but anormally closed check valve 3430 (as shown in FIG. 34) is usedalternatively. In one implementation, check valves are connecteddownstream of pressure transducers 340 which allow one reactor fromback-pressuring another reactor while providing independent pressurereadings of each reactor with the pressure transducers residing in thecontrol system. In other implementations, the check valves 326, 336 canphysically reside in the reactor 302 or in the control system 303 andprovide the same function. Additionally, the system can also include apressure regulator 344. At times, it may be desired to operate thereactor 302 at a higher pressure (e.g., 80 psi or higher). In oneexample, the regulator 344 can bring the pressure down to 25 psi.Alternatively, a regulator 344 with a dial, or other means of regulatingpressure, can be used, which would allow a user to change the outputpressure of the control system. Alternatively, an electronicallycontrolled regulator can be used to allow a microcontroller (such asmicrocontroller 387) to set the output pressure based on the desiredpressure. In a separate implementation, no regulator could be used atall, and the micro-controller could control the water flow rate andamount to control the output pressure of the reactor.

Material Feeds

Alternative reactant fuel material (e.g. sodium silicide) I liquid (e.g.water) mechanisms are possible. In some configurations, the reactantmaterial can be formed, molded, or pressed into geometrical structures.For example, rods formed from stabilized alkali metal materials can beinserted into an aqueous solution at a defined rate to control thereaction. Similarly, the rod may simply be removed from the water bath,or other aqueous solution, to stop the reaction. Additionally, reactantfuel materials can also be compressed into pellets. These pellets canthen be manipulated and placed into water, or other aqueous solutions,at a defined rate to effect the reaction.

Aqueous Solution Feeds

Water may be fed into reactor 302 in a number of different ways. Forexample, water can be fed into the reactor using a single water inlet338, or by using multiple water dispensing nozzles at select locationsas shown in FIGS. 4A-4D. In simple system configurations and for smallsystems, a single water input will suffice. For larger systems, multiplewater inputs can be used to facilitate the reaction and to aid in areaction re-start. For example, in FIG. 4A, a water feed tube 411extends vertically from water inlet 406 and employs multiple waterdispensing nozzles 413 with which to feed water to multiple areas of thereactor 402 using a single tube 411. Likewise in FIG. 4B, a horizontalwater dispensing filter spray 415 is also used to feed water to multipleareas of the reactor 402. In practice, a single or any number of tubescan be used. The tubes and water dispensing nozzles may be of variedsizes, and the water dispensing nozzle pattern and hole size may varyacross the tube to optimize the reactor mixing conditions. For example,small tubing may be used with a number of small holes, such as holeswith dimensions of 0.001″ to 0.040″ or larger in diameter, for example.Small holes can have a tendency to clog with reaction by-products whenattempting to restart a reaction, while larger nozzles can cause theaqueous solution to dribble onto the reactant fuel material rather thanjet or mist. When using a pump with high pressure capability, largerorifices can be used to inject water to the point of reaction. When lowpressure water feed system are used, more nozzles can be used to limitthe distance between the nozzle and points of reaction. Depending uponthe application and the specific reactants, any of the aqueous solutiondelivery techniques can be selected.

Additionally, the water feed tubes may be curved or spiraled as shown inFIGS. 4C and 4D. In FIGS. 4C and 4D, a spiral water feed tube 421 can beused to access multiple areas of the reactor 402 using a single tube.This spiral water feed tube 421 can have holes in a number of possiblepositions to maximize its coverage area and to minimize water saturationin one area of the reactor 402 with respect to another. The center post423 can also be included for mechanical support and for heat removal.For designs that do not require such support or heat removal structures,it can be removed. Additionally, a water feed network can be integratedwithin the center post 423. Other water dispersion configurations arepossible as well. For example, one implementation can employ anassortment of fine holes or mesh to facilitate water transfer. In otherimplementations, the water feed network may not be uniform through thevolume of the canister. For example, the feed network can be optimizedto feed directly into the reactant fuel area. If a reactor has an excessvolume for waste products or reactant foaming, the water feed networkmay not add water to these areas. Additionally, the water feed networkcan employ tubing configured to spray water on a membrane(s) used forhydrogen separation (discussed below). The tubing can include holes orit may contain additional array(s) of tube(s) or nozzles. In thismanner, water is fed directly to the reactant fuel in multiple areas ofthe reactor 402 to facilitate its reaction with the aqueous solution.

By feeding water into select locations of the reactor 402, the water andensuing reaction can be made to chum or mix the reactant fuel in thereactor 402. As hydrogen is formed and rises, the hydrogen gas serves tostir the reactor materials (that is, the aqueous solution and thereactant fuel materials) enabling near complete reactivity of thesereaction components. Mixing the reaction components can also beaccomplished by positioning both the hydrogen outlet and water inlet onone end of the reactor with downward orientation as shown in FIG. 6.This configuration provides a single connection plane to the hydrogengeneration system. The hydrogen pickup 666 is located at the top of thereactor 602 and the pressurized gas travels to the bottom through ahydrogen tube 668. This hydrogen tube 668 can be in or outside thereactor. Different configurations and tube geometries can also beemployed.

Less than complete reactivity can be employed, which may increase energydensity (H2 delivered I (mass of powder+mass of water required)) as theamount of water required is non-linear. In addition, partial reactivitycan leave the waste product in a near solid state as it cools from theelevated local reaction temperature. Solid waste products can bebeneficial for waste material disposal.

Heat Transfer

Returning to FIG. 3, as the reaction of the reactant fuel material 301and water progress, heat is generated inside the reactor 302. One ormore thermisters 328 can be used to measure the heat of the reactor 302and to control a cooling system, including one or more cooling fans 330that can be used to cool the reactor 302. Likewise, cooling may beprovided by a liquid cooling loop (not shown) using a self-containedheat management circuit, or by circulating water about the reactor 302from the water container 314 using a separate water cooling run. Ofcourse, thermister 328 may also control water supply valve 324 toregulate water flowing into reactor 302 to control the reaction basedupon the temperature of reactor 302, to control the amount of wasteproduct generated, to minimize water usage, to maximize reactivity, andfor other reasons.

As shown in FIG. 5, a heat removal structure 523 can be positioned inthe center of the reactor 502 as well. The heat removal structure 523may also facilitate a mechanical reactor locking mechanism by holdingboth ends of the reactor together when pressurized.

In FIG. 5, the bottom 572 of the reactor also serves as a heat sink andstand for the reactor 502. While some heat is removed through thereactor walls, when these walls are clear and made from glass orplastic, these materials typically have limited thermal conductivity. Inone implementation, a significant amount of heat is removed througheither or both ends 562, 572 of the reactor. One end of the reactor 502may exclusively be a heat sink (bottom 572) while the other end (top cap562) may contain the reactor control and connections such as hydrogenconnectors 508 and water connectors 506, relief valves 555, electricalconnections 577, 579 such as electrical feed-thru, electrical signalprocessing connections, system sensing connections, and structuralconnections. In FIG. 5, the entire body of the reactor 502 can be clearor translucent (e.g., made of glass or plastic), providing both afeature allowing for visual detection of the status of the reaction, anestimate of reactant fuel material consumption, as well a uniquepackaging and visual appearance. In another implementation, the reactorcan be generally opaque with a clear viewing window with which to viewthe reaction.

Additionally, as shown in the example of FIG. 7, the heat sink 723 andall components are connected on one end 762. This geometry facilitateseasy connection to the hydrogen generation system with gas connections708, fluid connections 706, and electrical connections 777, whileproviding a direct path for heat removal by the hydrogen generationsystem using air cooling, liquid cooling, or any other method.

Pressure Control

Returning to FIG. 3, burst relief valves, burst disks, or othercontrolled pressure relief points 330 can be implemented in the reactor302 to control its pressure. For example, when the pressure in thereactor 302 reaches a predetermined system parameter, hydrogen gas couldbe controllably vented from the reactor 302 through a pressure reliefpoint 330. In one example, a flow limiter can be used to limit thehydrogen output flow, to keep the flow within an allowable range fordownstream devices, and/or to keep the flow within the allowable ratefor successful filtration. The flow limiter can be an orifice or afunction of the check valve components. A flow limiter that limits waterinput to the reactor can be employed to avoid excessive instantaneouspressure generation.

The hydrogen generation system 300 can be configured to operate over arange of pressures. In one implementation, a user can set the desiredpressure limit, or range, using buttons, switches, or any othercommunications protocol (e.g., Bluetooth and the like) either directlyor remotely. In one implementation, the system 300 will monitor thepressure and control the reaction accordingly to maintain that pressurein the reactor 302 within a prescribed tolerance band. The system 300can be used for lower pressure applications (on the order of 25 psi) tofacilitate user safety and operational simplicity. Many fuel cellapplications operate in this pressure range. However, when necessary,sodium silicide can generate 1000's of psi for applications that requireit.

Hydrogen Filtration

In one implementation, the reactant fuel material is sodium silicide,which is combined with an aqueous solution to form hydrogen gas and aby-product (such as sodium silicate) as the primary reaction. Inpractice, other by-products can be formed, such as silanes (e.g., SiH4)when reacting under certain conditions. Borazine by-products can beformed when reacting mixtures with ammonia borane, and other items suchas water vapor or sodium hydroxide (NaOH) particulates are alsopossible. In addition, aqueous solution (e.g., water), liquid wasteproduct (e.g., silicate), and reactant fuel materials (e.g., sodiumsilicide) can all be present within the reactor. Multiple levels offiltration may be used to cause only hydrogen to exit at a level ofpurity applicable for the particular application.

A hydrogen separator can be used which may serve multiple purposes. Inone implementation, a separation media made of laminated Teflon (PTFE)with a pore size of about 0.45 micro-meters can be used. A wide varietyof pore sizes and specific material choices are available.Implementation features include high throughput gas flow-rate, a waterbreakthrough pressure up to 30 psi, and ultrasonic bonding to thereactor cap. Membranes are available in a wide range of material typesand thickness. Multiple membranes can be used to provide coarse and finefiltration. For example, when using sodium silicide as the reactant fuelmaterial in the aqueous solution reaction, hydrogen bubbles can residewithin a sodium silicate foam. During the reaction, this foam (orhydrogen coated sodium silicate bubbles) can coat a filtration membranewith a sodium silicate waste product. FIG. 8 shows a systemconfiguration that uses a coarse media filter 888 to break down thisfoam prior to performing a finer filtration using a hydrogen filtrationmembrane 890. In one implementation, a copper wire mesh is used as thecoarse media filter 888. This successfully keeps high viscosity materialaway from the fine filter hydrogen filtration membrane 890. Other coarsefilter media can also be used. Copper, other metals, or other materials,such as nylon or synthetic sponges, or material coatings, includingacids, bases, and water can be selected to include advantageous chemicalactivators or absorbents for either catalyzing hydrolysis or absorbingcontaminants. The fine filter membrane 890 material can also include abacking 894 between the membrane 890 and the mechanical housing 892.This backing 894 provides mechanical support to the membrane 890 whileproviding paths for the hydrogen to exit the membrane 890 and enter thespecific hydrogen output connections (not shown in FIG. 8).

By providing the coarse and fine filtration at the reactor assembly, thehydrogen gas generation system capitalizes upon volume constraints.Additional filtration within the hydrogen generator system and/or fuelcell system can also be provided. For example, the hydrogen generationsystems depicted in the figures can include removable filtrationdevices, such as a removable desiccant filter, for example. A chemicalfilter can also be used in the hydrogen generator system that can beserviced after a period of time. Alternatively, the filters can beconstructed of a larger size such that they do not require servicingduring the full product life of the reactor. For many fuel cellapplications, water vapor in the hydrogen gas output stream isacceptable due to the desired humidity requirements of the fuel cell.For other uses, such as in some laboratory environments, commercialuses, and some fuel cell applications where lower humidity is dictated,water vapor in the hydrogen gas output stream may not be acceptable, anda dryer filter can be employed. The hydrogen generation systems of theclaimed invention allow for a removable filter to facilitate commercial,laboratory, and fuel cell applications, for example. In addition, somefuel cell applications, such as refilling of metal hydrides, require dryhydrogen. A water absorption media and/or condenser 896 as shown in FIG.8 can be used in these applications as well. Any use of a condenser 896can facilitate the collection and return of water to the primaryreaction to minimize water waste from the reactor 802. The return ofwater to the primary reaction can be made directly to the water inlet806 or to another connection to reactor 802.

In another implementation, the reactors can be removable or fixed, andan access door, or other access port, can be provided to add reactantfuel material and/or to remove the reaction waste once the reaction iscomplete. For example, an access door can be incorporated as a reactorcover, or lid, 562 as shown in FIG. 5. Alternatively, in theimplementation shown in FIG. 5, any portion of the waste product can bestored within the reactor for later disposal or recycling.

Cleaning the Filters

When using sodium silicide as the reactant fuel material and water asthe aqueous solution in the hydrogen gas generation systems, the primarywaste product is sodium silicate, which readily absorbs water. In somereactor configurations, a significant amount of sodium silicate foamcauses blockage of the filtration devices over time. The highly viscoussodium silicate can clog the filtration devices. By applying water tothe sodium silicate, the viscosity changes, which allows for the sodiumsilicate to be washed away from the filter area. For example, in oneconfiguration shown in FIGS. 9A-9C, a section of the water feed network(such as reference numeral 338 in FIG. 3 as one example) has a portionof the water flow directed directly onto the filtration device(s), suchas coarse media filter 888 and hydrogen filtration membrane 890 shown inFIG. 8. The water applied to the filtration devices by water spray 909eventually drops back down to the un-reacted sodium silicide and is alsoreacted, but it first serves to clean the filter as part of its deliveryto the reactor. Reference numeral 909 in FIG. 9A shows a stream of wateraimed directly up to reach the filtration device. FIG. 9B shows afiltration device 999 b that was not cleaned during the reaction, andFIG. 9C illustrates a filtration device 999 c that was cleaned duringthe reaction by spraying 22 water on the filtration device 999 c. Asevident from the difference in the filter residue shown in FIGS. 9B and9C, by applying water to the filtration device, the filter does notclog.

Additional Filters

Alternative filter designs to the membrane/coarse filter assembly canalso be used. FIGS. 10A-10B show a number of different filter designs.For example, in FIG. 10A, a cone shaped filter 1010 can facilitatemovement of the sodium silicate foam across the filter 1010 resulting ina breakdown of the bubbles 1012. This cone-shaped filter geometry mayalso result in a movement of the foam to liquid collection zones in theupper corners 1014 a, 1014 b of the reactor 1002 and recirculation ofthe sodium silicate solution down to the base 1009 of reactor 1002 asshown by vertical arrows 1050, 1060 pointing downward. Additional designfeatures may be incorporated into the reactor 1002 itself to facilitatethis action. Such features can include canister cooling to facilitatecondensation on the reactor walls 1040, as well as a wicking material1071 in FIG. 10B to help move the liquid solution down the reactor walls1040 or other appropriate areas as shown by vertical arrows 1051, 1061pointing downward.

Multi-Chamber Reactors

Even with filtration devices described above, some amount ofnon-hydrogen and/or non-water can escape through the coarse filterand/or membrane. FIG. 3 shows a combination chamber 355 to facilitate aprocess for capturing reaction waste products, such as sodium silicate.The process of using combination chamber 355 of FIG. 3 is shownschematically in FIGS. 11A-11B using multiple filters and membranes.

FIGS. 11A-11B illustrate methods of waste capture and circulation. Inone implementation, waste capture and circulation is performed within adisposable reactor. In FIG. 11A, hydrogen gas is generated in the largerreaction chamber 1154 by reacting water and sodium silicide 1101, andhydrogen gas 1191 moves upward through the hydrogen membrane 1190. Someamount of sodium silicate, water, and other reaction products may travelthrough or around the membrane 1190 as well. The actual flow rate ofthese products is much lower than the flow rate of the incoming supplywater 1138. All of these products (output hydrogen 1191, incoming water1138, and reaction by-products) are combined into the smallercombination chamber 1155. Smaller combination chamber 1155 can besupported in reactor 1102 by supports 1133. A mesh filter 1122 can alsobe used to provide further incoming and outgoing filtration.

The incoming water 1138 absorbs the combined reaction by-productsbecause they are soluble in water. The water 1138 and the by-productsare then pumped back into the larger reaction chamber 1154. The outputhydrogen 1191 will travel upwards to the secondary membrane 1195, whichcan be of a finer pore size than membrane 1190. Some amount of watervapor and other components may still be in the final output streamlabeled “Pure Hydrogen Output” 1193. In some operational situations, thepressure in the combination chamber 1155 and reactor chambers 1154 mayequalize, and hydrogen will not flow through the membrane 1190.

To overcome the pressure equalization, the membrane/filter pressuredrops, check valve pressure drops, and specific operational controlmethods of the water pump can be modified prior to, or during areaction. As an example, cycling the supply pump can create pressureperturbations allowing for hydrogen to initiate or tore-initiate flow.An alternative waste product re-capturing configuration for a pump-lessconfiguration is shown in FIG. 11B. In FIG. 11B, an over-pressure of thesupplied water is used to feed water to the reactor.

Architecture Using Smaller Compartments within the Reactor

As outlined above, the reactors in these examples can be separated intomultiple compartments. This architecture can be useful for directingwater to different areas of the reaction. In one example, differentareas of the reaction can be operated at different times facilitatingeasier restart conditions as the reaction can start much quicker whenjust sodium silicide as opposed to when sodium silicide and sodiumsilicate are present. In addition, water sprayers have been shown to beeffective in controlling the reactions. Each sprayer can have a definedrange of water dispersion. A sprayer with a compartment approach canwork well to control the reaction. Various methods and materials toseparate the compartments can be used. For example, thin tubes can beloosely inserted in the reactor compartment, a honeycomb mesh assemblycan be integrated in the interior of the reactor, or a flexible membranenetwork can be incorporated into the reactor. Additionally, thematerials used to divide the reactor can seal off the aqueous solutionin one compartment from other compartments. Compartments can beconfigured in both horizontal and vertical directions within thereactor. The compartments can also be made of water permeable and/orhydrogen permeable materials or made of other material used for watertransport via surface tension forces.

FIG. 12A illustrates one implementation of such an approach where areactant fuel material can be rolled into a cigarette-likeconfiguration. As shown in FIG. 12A, the reactant fuel material can bewrapped in a membrane material that can distribute water all around thepowder and/or permeable hydrogen. Multiple rolled compartments 1204 a,1204 b, 1204 c, 1204 d, 1204 e, 1204 f, 1204 g, for example, can behoused within reactor 1202.

As the reactions take place in the rolled compartments 1204 a, 1204 b,1204 c, 1204 d, 1204 e, 1204 f, 1204 g, the reactor 1202 will generateheat. Another implementation of such rolled compartments is to arrangethe rolled compartments next to each other horizontally for a lowprofile package similar to a cigarette case. In addition to techniquesdiscussed above, heat dissipation can be conducted through the walls1296 of the reactor 1202 as shown in FIG. 12B. As the walls 1296 of thereactor 1202 get hot, a number of areas on the outside of the reactor1202 can be insulated using protective pieces 1288 or other insulationdevices. These insulation devices can be positioned on the outside ofthe reactor 1202 to enable a user to touch the reactor.

Determining the Status of the Reaction

After an aqueous solution is added to the reactant fuel, a reactionoccurs, and hydrogen gas is generated. There are many ways to determinethe status of the reaction and to verify the progress of the reaction.These techniques can include visually observing the reaction, timing thereaction, and measuring parameters of the reaction before, during, andafter the reaction. For example, parameters that can be measured before,during, and after the reaction include, but are not limited to, theweight of the reactants, the temperature, the amount of aqueous solutionin the reactor, the amount of reactant fuel in the reactor, the maximumamount of aqueous solution to be added to the reactor, the amount ofaqueous solution added by viewport or known characterization of a pump,electrical conductivity, pressure, hydrogen output measurements eitherdirectly or indirectly by way of fuel cell current, and the like.

For example, sodium silicide has minimal conductivity. However, oncereacted with water, the sodium silicate readily conducts electricity ata level suitable for detection and measurement. While many differentmethods can be used to measure this change in conductivity, oneimplementation is shown in FIG. 13, where different electrical contacts1366 are placed on a ribbon cable 1350 inside the reactor 1302.

The electrical conductivity measurement circuit reads and comparesactual resistance measurements between pads 1313 a, 1313 b, 1313 c, 1313d, 1313 e, 1313 f and/or looks for point-to-point conductivity betweenpads 1313 a, 1313 b, 1313 c, 1313 d, 1313 e, 1313 f. These measurementscan be made using as few as two pads or as many pads as required toprovide sufficient state-of-reaction resolution. Similarly, contactprobes can be placed in different locations of the reactor to performsimilar readings and accomplish a similar effect.

Further, in another example, a single probe can contact two electricaltips to measure the resistance at a particular point at a very specificdistance in the reactor. This technique can be used in a configurationwhere an electrically conductive reactor is employed. In a similarimplementation, a single probe, multiple probes, or conductive pads maybe used, and the reactor itself can be used as a measurement ground.

In one configuration, the electrical contacts are connected to thehydrogen generation system via a number of electrical contact methods,such as spring loaded contact pins, swiping pins, blade insertiondevices, wireless transmission, or any other method of electrical signaltransfer. One reactor example using such contacts is shown in FIG. 14where electrical contacts 1414 connect to the pressure vessel cap 1416of a reactor. A recessed ribbon cable 1418 connects the contacts 1414 toa microcontroller 1420 in the pressure vessel cap 1416. The hydrogengeneration system can include detection circuitry effected byprogramming instructions in the microcontroller 1420 to interrogate orprobe the contacts 1414, to measure the resistance, and/or to determinea short circuit and/or an open circuit. The microcontroller 1420 caninclude programming instructions and algorithms to interrogate thecontacts 1414, determine a signal level, and convert the signal level toa conductivity measurement and to equate the conductivity measurement toa status of reaction measurement. Of course, the microcontroller canreside on the reactor assembly (such as in the pressure vessel cap 1416in FIG. 14) or in the control system 303 as shown in FIG. 3.

In another example for determining the state of the reaction, a forcesensor, such as a strain gauge, can be used to measure the weight of thereactor. Over the state of the reaction, the reactor becomes heavier dueto the water added to the sodium silicide. The change in weight of thereactor can be measured using a scale or other force sensor to determinethe weight of reaction before, during, and after. By weighing thereactor during these periods, the status of the reaction can bedetermined as well as other system specific parameters such as reactionefficiency, completion percentage, a time of reaction, the amount ohydrogen gas generated from the reaction, and other parameters.

The control system can adjust its pump parameters based on the state ofreaction. For example, reactions can require more water to generate thesame amount of hydrogen near the end of the reaction than the beginning.The microcontroller can use this system parameter to predict thereaction characteristics enabling more uniform hydrogen generation byadjusting other control measures, such as temperature ranges, pressureranges, and the amount and speed at which the aqueous solution is addedto the reaction.

Displaying Reaction Status and Reaction Parameters

Regardless of the measurements used to determine the status of thereaction, as shown in FIG. 2, display devices 218 may be used to monitorand control the reaction of the reactant fuel and the aqueous solution.Display device 218 can include an LCD (liquid crystal display) or otherdisplays to show the determined force or weight of reaction and otheroperating or system specific parameters. An additional example displaydevice 318 is shown in FIG. 3. For example, the display device 318 candisplay the actual weight, or use a microcontroller (such asmicrocontroller 387 in FIG. 3) to convert the actual weight to acompletion percentage, a time, or to another measure related to thestatus of the reaction.

Single Compartment Reactor Example

An example lightweight, low-cost, reusable reactor 1502 is shownschematically in FIG. 15A and in detail in FIG. 15B. The thin-walledreactor 1502 is stamped and formed to include a lip 1553 around thecanister cap 1555. A separate support piece 1557 is placed on theunderside of the lip 1553. The canister cap 1555 and support piece 1557compress the lip 1553, facilitating a strong reactor 1502 while using avery thin walled canister that all can be disassembled and re-used. Thelip 1553 facilitates a mechanical connection to secure the canister cap1555 using a retaining ring without gluing or crimping. This providesthe capability of removing the canister cap 1555, servicing the reactor1502 and cap 1555, then refilling and reusing the reactor 1502 and cap1555. Servicing the reactor 1502 and cap 1555 can include replacing orrefurbishing component pieces, such as separator membranes, filtrationmedia, and the like. Additionally, protective methods, such asencapsulation or other methods, can be used to avoid tampering with thereactor and/or to provide reactor tampering detection.

FIG. 15C shows a detailed drawing used in the manufacturing of such athin walled vessel including the designed over-lip 1553. As also shownin FIG. 15B, the over-lip 1553 can be omitted if other methods are usedto attach the reactor cap 1555, such as crimp or glue-on approaches. Thebottom section 1563 of the cap 1555 can be designed to minimize weightand maximize strength while providing practical connection devices(collectively shown as 1565) such as aqueous solution inputs, hydrogengas inputs and outputs, electrical connection devices, and the like.

As further shown in FIG. 15B and described operationally above withregard to FIG. 3, the reactor 1502 includes both a hydrogen exit 1544and water inlet 1591. These connections may contain check valves and/ornormally closed shut-off valves, or other devices to regulate water andhydrogen flow. An example of a normally closed shut-off valve 3434 isshown in FIG. 34. The normally closed shut-off valve 3434 can beinstalled in the reactor on either the hydrogen exit 1544 and/or thewater inlet 1591 as shown in FIG. 15B. A mating component 3535 shown inFIG. 35 is mounted on the control system and has an O-ring 3537 orover-molded gasket on the surface of the mating component 3535, whichtouches and depresses on the surface of the normally closed shut-offvalve 3434. As the surface of mating component 3535 depresses on thevalve assembly 3434, the inner portion of shut-off valve 3434 slides toprovide an open fluid channel. In the un-opened state, the spring 3430pushes on the body of valve 3434 and causes an O-ring to seal and allowliquid to flow. An additional O-ring is used as a dynamic seal, whichkeeps the valve void volume to a minimum, which significantly reducesthe amount of normal air added to the hydrogen gas when being connectedand disconnected. The body of valve 3434 includes threads 3439 so thebody may be screwed into the canister cap 1555. The valve 3434 can beinstalled and held in place by many other mechanisms such as by glue,press-fit, snap-ring, and the like.

The reactor shown includes integrated safety relief valves 1538 and1588. The safety relief valve 1538, 1588 can be implemented inalternative methods such as a one-time controlled pressure relief burstpoint. In FIG. 15B, one relief valve 1538 is used to vent pressurethrough the filtration while another relief valve 1588 may be used tovent pressure prior to filtration. In one implementation both valves1538, 1588 are set to relieve at the same pressure. In anotherimplementation, the post filter valve 1538 is set to relieve at a lowerpressure than a pre-filter valve 1588. In the event of an unattendedhigh pressure event, the system will vent all of the high pressurehydrogen through a filtered output. The secondary valve 1588 can alsoserve as a backup valve in the event of a high pressure event where thefilter is clogged. In another implementation, a dip tube 1543 isconnected to the gas channel of the relief valve 1588 and directed tothe bottom of the canister to vent the canister if stored upside down.In a version of this implementation, the dip tube 1543 can containporous filter media at the top, bottom, or both to selectively venthydrogen versus sodium silicate or other aqueous solution elements.

The cap 1555 includes an RFID chip 1522, such as an Atmel TK5551 RFIDchip, for example. Three thin-walled tubes 1539, 1541, 1543 are shownwithin the reactor 1502. One tube 1539 brings down water from the centerof reactor 1502 and includes integrated nozzles 1549 a, 1549 b, 1549 cto direct water flow to the areas of the reactor 1502 in which thereactant fuel is present. Another tube 1541 is horizontal to the planeof top cap 1561. This tube 1541 sweeps around the filter 1561 and sprayswater across the filter 1561 to clean the filter 1561 and to further thereaction between the aqueous solution and the reactant fuel.

As discussed above with regard to FIG. 3, a check valve (not shown inFIG. 15) can be placed in line with the water line in the reactor 1502.As described above, the check valve can be located in the controlsystem, in the reactor 1502, or in both. Water is pumped into thereactor 1502 through the previously described water network. As hydrogenexits the reactor 1502 via hydrogen exit 1591, the hydrogen gas can bepassed through a check valve (not shown in FIG. 15) as well. Asindicated above, the hydrogen gas output check valve can also be locatedin the control system (shown in FIG. 3 as reference numeral 303), in thereactor 1502, or in both. In systems utilizing more than a singlereactor 1502, a check valve is used for each of the hydrogen exit linesfrom each reactor. Also, independent pressure transducers can be used tomeasure each reactor pressure separately, and the independent pressuretransducers are then connected to the hydrogen exit lines either in thereactors or in the control system but prior to at least one check valveor other downstream isolation mechanism.

Check valves can be used to prevent one reactor from back-pressuringanother. Other components, such as normally closed valves or flowcontrol regulators, can be used to accomplish similar results.

As described above with regard to FIG. 3, hydrogen gas can pass directlyout of reactor 302. In another implementation, the hydrogen gas canfirst pass through a high purity contamination filter. Similarly, asshown again in FIG. 3, the hydrogen output can be bubbled through awater tank/condenser, such as the original water tank 314 or a separatewater tank. This serves to condense some amount of water vapor and tocapture some amount of particulates or contaminants that may be presentin the outputted hydrogen gas.

After bubbling through the water tank 314, the outputted hydrogen gascan be passed through a fine high purity filter 369. The water tank 314can include additives for low temperature operation or for otherpurposes. Additives can include a coreactant that increases the amountof H2 produced, a flocculant, a corrosion inhibitor, or a thermophysicaladditive that changes thermophysical properties of the aqueous solution.For example, the thermophysical additive can change the temperaturerange of reaction, the pressure range of the reaction, and the like.Further, the additive to the aqueous solution can include mixtures of avariety of different additives.

Some additives can facilitate less contamination in the outputtedhydrogen stream, or the additive itself can serve to do hydrolysis onany developed silane (SiH4) produced in the reaction. Hydrogen gas fromreactor 302 can be directed to an aqueous filter 351. A pressuretransducer 340 can be used to measure and regulate the pressure of thehydrogen gas. An aqueous filter 351 is used to perform hydrolysis on anydeveloped silane, collect particulates, and condense water from thehydrogen output stream. In the event of hydrolysis of silane, a smallamount of Si02 and hydrogen would be generated. The produced hydrogencan be used in the hydrogen gas output 365 and the Si02 can be pumpedinto the reactor 302 with the remaining water through valves 361, 324.The water tank 314 can be drained and cleaned as necessary. If bubblingoutputted hydrogen through water, the water tank 314 can also have apermeable membrane 367 in the top to allow hydrogen to exit at hydrogenexit port 365, but not allow water to exit in a severe tilt or flippedupside down situation. In one implementation, the water lid 363 has acap contact sensor 311 or other detector that notifies themicro-controller 387 once the water lid 363 is fully closed. In oneimplementation, the microcontroller 387 can turn off an output valve 362before the water tank 314 to let the reactor(s) stay pressurized whilemore water is added.

In other examples, an output valve 366 can be placed after the exit ofthe water tank 314 and the fine filter 367. This output valve 366 is canbe controlled by the microcontroller 387 to start the reaction and allowthe pressure to build to an appropriate level to supply the outputtedhydrogen gas to an end application, such as a cell phone, a laptopcomputer, a residential electrical grid, and the like. Another exampleincludes a separate relief valve 368 or a bleeder valve to purge thesystem of any trapped air. As discussed above, a further exampleincludes a filter 369, such as a condenser or desiccant filter, in linewith the output hydrogen line to support particular applicationrequirements as applicable.

Another example can include routing all water from reactor 302 through asecondary combination chamber 351. Additionally, another exampleincludes pumping input water into secondary combination chamber 351 as adirect pass on its way to the reactor 302 or with independent control tothe secondary combination chamber 351. The secondary combination chamber351 can be coupled to the thermal control system, including thermister328 in order to increase and/or maintain the temperature of thesecondary chamber in order to facilitate hydrolysis and/or filtration,much as thermal control was provided with regard to the reactor 302 asdescribed above.

Additional Electrical Connections

In both single compartment reactors and those reactors with additionalcompartments, additional electrical connections can be made to provideaddition information to a user regarding the status of the reaction andthe system specific parameters. For example in FIG. 3, additional signalconnections (either wired or wireless) can be made from reactor 302 andcontrol system 303 to control electronics 386 to provide control devicesand display devices measurement data with which to monitor and displaysystem specific parameters.

For example, one or more read/write RFID devices can be used to assessthe state of the reaction by storing and reporting system specificparameters. For example, microcontroller 387 can write data indicativeof the amount of water pumped into the reactor 302 to an RFID device333, which could be placed in a cap of reactor 302. Based on the amountof measured water known to be inserted into the reactor 302 and withother measurements such as pressure and temperature measurements, thestate-of-reaction can be determined by the system 300. Similarly,additional RFID devices 381, 382, 334 can be incorporated throughout thereactor 302 and control system 303 to provide and store systeminformation to and from microcontroller 387. For example, each RFIDdevice can include information such as a serial number, an amount ofwater inserted into the reactor, the total allowable amount of waterthat can be inserted into the reactor, the pressure in the reactor, thepressure in the water container and elsewhere in the system. Thepressure measurements, temperature measurements, amounts of water, andother system characteristics in the RFID devices can then be used todetermine the state of the reaction. Similarly, microcontroller 387 canwrite other system parameters, such as the water flow velocity, amountof hydrogen produced, and other parameters to RFID devices 333, 334,381, 382 and other RFID devices that can be placed in control system303, in reactor 302 and throughout the reaction devices.

Additionally, an RFID device (not shown separately) can be integratedinto the reactor 302 to provide inventory management by individuallyidentifying the reactor 302. This device can be used separately forinventory management, or a single device can be used in conjunction withmultiple set of control functions. The RFID devices can communicate witha transponder and/or a number of transponders that can be used inmultiple locations. For example, transponders can be used at a factorymanufacturing reactors as part of an assembly line or as a hand-helddevice for quality control. Likewise, transponders can be located inmating hardware for use in the field. The mating hardware can include ahydrogen generation system, a fuel cell system, a complete power system,or other interface system.

Passive Hydrogen Generation

An example of a passive architecture reactor system 1600 is shown inFIG. 16. “Passive architecture” refers to the lack of an electrical pumpto initiate the reaction. Passive architecture systems are oftensuitable for low output systems. With this architecture, overheadoperations can be minimized. For example, components of low outputsystems can often be combined into smaller numbers of physical packages,and other components can be eliminated altogether. For example, the fanand pump of a reactor system can be eliminated for a low power systemsuch as a cell phone or a cell phone recharger and other applicationswhere low power is required and both the volume and cost must beminimized. A simplified architecture of a pump-less system for sodiumsilicide based (or other aqueous reactive material) hydrogen generationis shown in FIG. 16. The water tank 1614 is initially pressurized byeither connecting a pressurized source 1616 or a pump. Water is then fedthrough the water supply line 1690 which can also include a flow-limiter1624. The flow-limiter 1624 can be an active component, such as a valve,or a passive component, such as an orifice. Alternatively, gravityitself may provide the initial force to move water through the watersupply line 1690. As the initial water enters the reactor 1602 andcombines with the sodium silicide 1601, hydrogen 1634 is generated andcreates hydrogen pressure, which in turn re-pressurizes the water supply1684 via re-pressurization line 1643. The pressure at the hydrogenoutput 1666 will drop as hydrogen begins to flow out of the system andback to water tank 1614. However, the pressure at the water tank 1614 ismaintained due to the check valve 1677. This creates a pressuredifferential driving more water into the reactor 1602, which thenre-pressurizes the system 1600. As the pressure increases, the totalsystem pressure balances, which stops the water flow. Flow-limiter 1624can be used to control the rate of water input to reactor 1602.Otherwise, excess water could be inserted into the reactor 1602 beforethe hydrogen pressure has had time to develop, which could potentiallylead to a positive feedback situation, and the reaction would occurprematurely.

In addition, the water supply may come from either the bottom of thewater tank 1614 or through another exit point (such as the top) on thetank 1614 when a water pick-up line is used (not shown in FIG. 16).Gravity or siphoning water feed mechanisms can also be incorporated intothe system by appropriate placing of the water inlet and exits.

The architecture of the low output reactor system 1600 is incorporatedinto a complete reactor assembly 1700 in FIG. 17. The reactor 1702includes reactant fuel 1701 in a reactor chamber 1722. The reactorchamber 1722 can include membranes 1733 with which to contain thereactant fuel 1701 and provide an escape path for generated hydrogengas. The reaction chamber 1722 can be either a rigid chamber or aflexible chamber. The reaction chamber 1722 can have membranes 1733 inmultiple locations to enable the reaction chamber 1722 to be oriented inany number of directions. Surrounding the reactor chamber 1722 is thepressurized hydrogen gas 1788 within the outer hydrogen chamber 1793,which flows out the output valve 1766 as required by the particularapplication. As was the case with the general low output reactor system1600 is shown in FIG. 16, water 1734 is supplied to reactor 1702 througha water supply line 1790. Water 1734 can be provided to the system bywater displacement pump 1716 or by an external water source throughwater fill port 1717. Water repressurization is effected by waterre-pressurization valve 1777. In this fashion, low output reactor system1700 can provide hydrogen gas to an end application.

The reactor chamber 1722 can be fed with multiple water feed mechanisms.For example, a small pump can be integrated within the reactor 1702 toprovide a fully disposable reactor with a reactor chamber, water, andpumping system. This pump can also be separated from the reactor. Oneexample of a system with a separate pump is a spring driven system shownin FIG. 18.

FIG. 18 illustrates a spring driven reactor system 1800 with anintegrated reactor chamber 1802, water supply 1814, and “pumping system”1820. The reactor 1802 can also include a water spreader (discussedbelow with reference to FIG. 25). One example spring driven reactorsystem incorporates a spring 1821 that pushes on a sliding piston 1831and applies pressure to a water chamber 1841, including water supply1814. Additional implementations can also be employed with differentpiston alternatives, such as a flexible material, elastomers, bellows,or other structures that provide movement when a differential pressureis applied across them. In the case of a spring, a small platform area1851 can be in contact with the edge of the spring 1821 to distributethe force over a greater area. Additionally, an example of a springdriven reactor system that is fabricated into a single body package 2100is shown schematically in FIG. 21 and pictorially in FIGS. 22A and 23.FIGS. 22B and 24 provide exploded views of the spring driven reactorsystem in a single body package 2100.

Returning to FIG. 18, as the spring 1821 develops pressure in the waterchamber 1841, water is injected into the reactor chamber 1802. Hydrogenis generated as water contacts the reactant fuel material. As hydrogenis generated, this creates pressure in the reactor chamber 1802, whichstops the inlet of water. In this implementation, the water feedmechanism is orientation-independent. In the reactor system 1800 of FIG.18, the reactor chamber 1802 is not orientation-independent, becauseaqueous solution could block the filter 1890, not allowing the hydrogento pass thru when the system 1800 is upside down. To compensate forthis, a reactor membrane system, such as the reactor chamber withmembranes shown as reference numeral 1722 in FIG. 17, can be implementedwith multiple pickups. Additionally, a check valve 1824 can be placedbetween the water feed 1814 and the reactor chamber 1802. Without such ahydrogen delivery system, hydrogen pressure pushes pack on the spring1821 with excessive pressure, which in turn injects excessive water. Thelack of a check valve could create an oscillatory system. For example,FIG. 19 shows an example pressure response over time in a system withouta check valve. As shown by the graph in FIG. 19, an oscillatory pressureresponse is evident when pressure equalization means, such as a checkvalve, is not incorporated into the system.

In contrast, FIG. 20 shows an example pressure response over time in asystem utilizing a check valve. The pressure response in FIG. 20 doesnot exhibit an oscillatory response and instead shows a steady decayassociated with the spring pressure.

As also shown in FIG. 20, an initial peak at the beginning of thereaction occurs as an initial slug of water is injected into thereactor. This effect can be dampened using a water flow restrictor, orit can be increased to create a momentary transient level of hightransient hydrogen generation to facilitate fuel cell stack purging. Forexample, in addition to the check valve 1824, a method to slow the waterflow during restarting condition can be implemented using a water flowlimiter. During a restart, the instantaneous hydrogen pressure can dropto a very low value, creating an injection of water that could result ina large reaction spike. A flow limiter function can be incorporated intothe water distribution function to prevent such an effect. The use of acheck facilitates near constant pressure operation as determined by thespring design. Other mechanisms for the check valve feature can also beused, such as a control valve or regulator, and the like.

Spring-driven reaction systems can use the characteristics of the springto monitor and determine the amount of the reactant fuel material thatremains in the reactor chamber. The determination can be made eitherdirectly or indirectly. With a known amount of reactant fuel in thereactor chamber at the beginning of a reaction, the pressure in thereactor chamber is monitored. As the pressure inside the reactorchanges, the amount of water added to the reaction can be determined,which provides an indication of the amount of reactant fuel materialthat was used in the reaction. Subtracting the amount of reactant fuelmaterial used from the amount of reactant fuel material at the start ofthe reaction provides the amount of reactant fuel material remaining foruse in the reaction. For example, at the beginning of a reaction, aknown amount of reactant fuel material is added to the reactor chamber.A spring, such as spring 1821 in FIG. 18 or in FIG. 21 develops pressurein the water chamber 1841, and water 1814 is injected into the reactorchamber 1802. Hydrogen is generated as water 1814 contacts the reactantfuel material 1834. As spring 1821 provides the pressure to inject water1814 into the reactor chamber 1802, hydrogen is generated, which createspressure in the reactor chamber 1802. The pressure created in thereactor chamber 1802 applies an opposite force on water chamber 1841.When the pressure in the reactor chamber equals the water pressurecreated by the flow, the water flow will stop, which in turn means thatadditional hydrogen generation will also stop. In the event that thehydrogen pressure in the reactor chamber inadvertently exceeds the waterpressure created by the water flow, the check valve will not allow thewater to develop a higher pressure than the pressure determined by thespring. Without the check valve, the system could oscillateuncontrollably. As the reaction continues over time, the effectivespring force can be seen as decaying over that same time period due toforce versus deflection characteristics of the spring. As thedisplacement of the spring changes over time, this results in a changein water pressure over time, which also equates to a change in theaverage hydrogen pressure in the reactor chamber over the same time. Ameasurement of spring displacement, water volume, water pressure, orhydrogen pressure can be therefore used to indirectly determine thestate of the reaction. For example, the system may be characterized sothat at the beginning of the reaction, the developed pressure in thereactor chamber is 3 psi but near the end of the reaction, the pressurein the reactor chamber is 1 psi. The state of the reaction can bedetermined by observing the amount of water added to the reactor using aviewing window in the reactor and/or the water supply. For example, theviewing window can include tick marks or other calibration designationsto indicate the amount of water added to the reactor. Additionally, amicrocontroller with a look-up table (database) can be used to measurethis pressure and to determine the state of the reaction. The pressuresensor and the microcontroller may reside in the water supply, in thepathway between the water supply and the reactor chamber, in the reactorchamber, or in any combination of them.

The spring force is based upon the physical characteristics of thespring, such as material, wire diameter, diameter of the shaft, internaland external diameters, pitch, block length, free length, number ofcoils, spring rate, and lengths at force. The spring can be of any of awide variety of different types such as coil, leaf, or clock springs,for example. Furthermore, the spring can be an elastomer, such assilicone, and stretched to provide a force with which to move the waterto the reactor. The silicone can be configured as a balloon or as otherelastomeric and/or elastic devices to impart the force. Based upon thesephysical characteristics, the effective force produced by the spring canbe used to determine the hydrogen pressure in the reactor chamber, theamount of reactant fuel material that has been reacted or similarly, howmuch reactant fuel material remains in the reactor chamber. Likewise,the effective spring force can be monitored using a force gauge, such asforce gauge 1888 to monitor and determine the effective force of thespring and thereby the pressure produced by the hydrogen gas. Of coursethe force gauge 1888 can also be installed in the reactor chamber tomonitor the hydrogen pressure produced from the reaction. Similarly, apressure gauge can also be used. From these volume, pressure, and/orforce measurements, the amount of reactant fuel material remaining inthe reactor chamber can be determined. For example, a simple look uptable and/or database mapping can be used to map effective spring forceto the amount of reactant fuel material remaining in the reactorchamber. Likewise, a similar table can be employed mapping the hydrogenpressure in the reactor chamber to an amount of reactant fuel that hasbeen reacted. A similar table equating water volume added to thereaction to an amount of reactant fuel that has been reacted can also beused. Combinations and variations of these database mappings/look uptables can also be employed.

In the passive architecture reactor systems, the water spreading anddistribution can be performed using a number of techniques. For example,as shown in FIG. 25, the water spreader 2515 can be a small diametertube with small distribution holes 2513. The water distribution systemcan also incorporate a network of holes in a silicone tube 2555 as seeninside the reactor cavity 2502. The hole spacing, sizing, and typevariability has been described above with regard to the nozzles.Additionally, the hole sizes in the silicone tube 2555 structures canprovide additional flexibility. As outlined above, small holes can besubject to clogging by the generated reaction waste products, so the useof silicone tubing 2555 can allow for the pressure to create a widerhole opening up around a clog and then forcing the blockage out of thehole. Other water distribution mechanisms such as borosilicate fibers,for example, and other water wicking materials can also be used todistribute water throughout the reaction area. These water distributiontechniques can be used with any type of pump or control systemarchitecture.

As shown schematically in FIG. 18, one example of a two-part reactorsystem 1800 includes the reactant fuel material 1834 in one primarycomponent or container such as reactor 1802, and the aqueous solution isinitially within another primary component or container, such as aqueoussolution canister 1892. The reactor 1802 can be disposed of or recycledonce the reaction is complete, while the aqueous solution canister 1892is reusable and refillable by a user. These two primary components 1802,1892 are termed a “reactor and water feed system.” In the example shownin FIG. 18, a complete hydrogen generation system is made up of two corecomponents: a reactant fuel reactor 1802 and an aqueous solutioncanister 1892. These two separate canisters 1802, 1892 are connectedtogether, and interact to generate hydrogen gas. Alternatively, asdiscussed above, these two canisters 1802, 1892 can simply be connectedtogether through a water inlet valve, while a control system (e.g., fuelcell system, consumer end product, and the like) provides the mechanicalrigidity to hold the canisters in place and release them accordingly.Furthermore, the entire water feed system can reside within the controlsystem as a non-separable and/or removable component.

An interface valve 1824 can reside in the reactor 1802, in the feedsystem 1892, and/or in both. When the reactor 1802 and the water feed1892 are connected, the interface valve may not allow hydrogen pressureto deflect the spring 1821. This can be accomplished by includingfeatures of a check valve or a controlled on/off valve in the interfacevalve 1824. In a separate implementation, if the interface valve 1824does not provide such feature, separate features can be employed toprohibit reverse movement of the spring, such as controlling the pistonassembly with a screw drive or other mechanism that does not allow thewater fed system to be significantly pressurized with hydrogen gas.

FIGS. 22-24 show example core components in this system implementation.As shown in FIG. 22B, a metal spring 2121 is employed in the watercanister 2192 to generate pressure and to provide a means for water toflow into the reactor canister. The metal spring 2121 in this example isa tapered conical extension spring, but other spring types can also beused, such as torsion, clock, inverted tapered conical, compression, andothers. The spring 2121 can be mounted securely to the base 2170 of thecanister 2192, and to a plunger 2172. Furthermore, the spring 2121 iscentered to prevent plunger yaw. The plunger 2172 shown in FIG. 22B hasintegrated features to guide and seal as the plunger 2172 slides, butother water delivery designs can be used. For example, as discussedabove, a different example can employ a flexible “bag,” which deliverswater under compression to a reactor.

A check valve 2162 and orifice 2164 (shown in FIG. 23) are incorporatedinto the water outlet between the water canister 2192 and powder(reactor) canister 2102. The check valve 2162 serves to prevent hydrogenpressure from re-pressurizing the water canister 2192, and thus preventssystem instability. In other examples, the check valve 2162 can alsoseal upon water canister/reactor disconnection. In other examples, thecheck valve 2162 can also relieve pressure if excessive pressures aredeveloped in the system. The orifice 2164 serves to limit water flow tothe reactor 2102 during periods of high differential pressures betweenthe water and reactor canisters 2102, 2192.

As shown in FIGS. 26 and 27, in other implementations, the reactor andwater feed sub-systems are separable. For example, as shown in FIG. 26,one example implementation employs a threaded locking mechanism 2666 tocouple the two canisters 2102, 2192. Other locking designs can also beused such as a click to lock mechanism, or fine (10-32) internal andexternal threading on the water feed port. The threads of the lockingmechanism do not have to seal against water or hydrogen, and 0-ring orgasket type seals can be used to couple the water to reactor canisterinterface.

The canisters in this example are both thin walled pressure vessels asdescribed above. The reaction canister can be constructed with basecorrosion resistant materials, such as nickel plated, or epoxy coated,aluminum and the like, or engineered rigid or flexible plastics. Thewater canister can be constructed from light metals or engineeringplastics. The water canister can have a locking mechanism that preventswater flow when the canisters are disconnected or removed. The lockingmechanism can be a mechanical latch that requires user intervention forwater to flow. Alternatively, the reactor can contain a valve or othermechanism which stops water flow until there is user interaction.Example user interactions include a physical switch or a valve actuatedby a motion of inserting the canister into fuel cell system assembly.

Additionally, the spring as part of the water feed system can beconfigured to be outside the water as shown in the example of FIG. 27 orinside the water as shown in FIG. 28. If the spring is located insidethe water, corrosion inhibitors can be added to the aqueous solution orthe spring materials can be properly selected to limit corrosion.

As shown in the examples of FIGS. 29A and 29B, a number of differentconfigurations can be used to keep a near constant water pressure theentire time of water insertion into the reactor. The springs can beselected so the actual travel distance is short in relation to the totalcompression distance. One method to accomplish this is by using aninverted conical spring as shown in FIGS. 29A and 29B. A longuncompressed spring 2921 can be compressed and inverted (as shown inFIG. 29B) so that it pulls down flat while still under pressure. Thisenables the spring compression volume to be minimal while stillproviding the necessary force.

Volume Considerations

Some users may require configurations that are as small a volume aspossible with all of the required water included within the package tominimize user complexities. In one example shown in FIGS. 30A and 30B,the reactor volume 3002 starts off small initially and grows over timeas aqueous solution is depleted and added to the point(s) of reaction.The reactor volume 3002 starts off in a very compressed state. Overtime, a piston 3072 or similar mechanism is used to exchange reactorvolume 3002 for water feed volume 3014. The driving force behind thiscan be a dynamic pumping mechanism, a spring driven mechanism, or othermechanism. In one implementation, the system is designed so that thegenerated hydrogen pressure does not contribute to the water deliverypressure by use of a screw-drive piston assembly, expanding gasket, orthe like. In another implementation, the system is designed so that thegenerated hydrogen pressure does not contribute to the water deliverypressure by use of a control valve or pressure regulator as part of thewater delivery system. With the spring driven mechanism shown in FIG.30B, an inverted tapered spring 3021 is shown which allows forminimization of the water feed volume 3014 at conclusion of the reactionwhile still providing an acceptable force as the spring assembly cancompress to be near flat while still being in an unrelaxed state. Thisapproach uses a comparable piston (or other method), an aqueous solutiondistribution network, an aqueous solution flow limiter, and anintegrated check valve or comparably functioned component (not shown).Mechanisms may be employed which mechanically lock the spring in placeor stop aqueous solution from flowing, such as a valve or othermechanism. The aqueous solution may flow on the outside of the cartridgeand can be routed through the piston geometry. Valves, regulators, orother control components can be used on the water feed line as well.Geometries and designs may be employed so that only force applied by thespring creates water displacement. For example, mechanisms such asthreaded interfaces can be incorporated so that an instantaneousincrease in hydrogen pressure does not translate to an instantaneousincrease in water pressure. Other features such as an expanding bellowsand others can be employed. Additionally, FIGS. 31-33 show a largerversion of a cartridge 3100 that can be used in systems such as fuelcells for laptop computer power.

Having thus described the basic concept of the invention, it will berather apparent to those skilled in the art that the foregoing detaileddisclosure is intended to be presented by way of example only, and isnot limiting. Various alterations, improvements, and modifications willoccur and are intended to those skilled in the art, though not expresslystated herein. These alterations, improvements, and modifications areintended to be suggested hereby, and are within the spirit and scope ofthe invention. Additionally, the recited order of processing elements orsequences, or the use of numbers, letters, or other designationstherefore, is not intended to limit the claimed processes to any orderexcept as can be specified in the claims. Accordingly, the invention islimited only by the following claims and equivalents thereto.

The claimed invention is:
 1. A system for generating hydrogen gas, thesystem comprising: a reactor including a solution inlet port and ahydrogen outlet port; a reactant fuel material added to the reactor; awater feed system with an elastomeric solution chamber that imparts apositive pressure to and delivers an aqueous solution via the solutioninlet fill port to the reactant fuel material in the reactor to generatehydrogen gas to be routed via the hydrogen outlet port to an industrialapplication.
 2. The system of generating hydrogen gas of claim 1,wherein the reactant fuel material includes at least one of sodiumsilicide powder or sodium silica gel.
 3. The system of generatinghydrogen gas of claim 1, further comprising: a check valve thatregulates the pressure of the aqueous solution delivered to the reactantfuel material in the reactor based upon characteristics of the spring.4. The system of generating hydrogen gas of claim 3, wherein the checkvalve regulates the pressure of the delivered aqueous solution as asteady decay associated with the spring force.
 5. A method of generatinghydrogen gas, the method comprising: inserting a reactant material intoa reactor; imparting a force from an elastomeric solution chamber thatpressurizes an aqueous solution in the solution chamber; delivering thepressurized aqueous solution with a water feed system via a solutioninlet fill port to the reactant material in the reactor to generatehydrogen gas; and, routing the generated hydrogen gas from the reactorvia a hydrogen outlet port to an industrial application.